My wife has a 99 Honda Accord 4cyl, auto transmission car with 78k on it. The problem is it makes a whistle noise when slightly accelerating on the gas. The noise will go away when you step on the gas hard. You can clearly hear it cruising at 55mph. The car also only does it when it is warm. The noise is also there when the transmissionis in park,or any other drive gears, but goes away when you put it in neutral? This has been going on for 2 years, and seems to be getting louder. My mechanic has cleaned the throttle body,and seemed to help only a little bit. He does not know what it could be. There are no performance problems with the cars, no codes have come up. Please advise with your comments if You could help Me. My next step is to go to the dealer, and be at there Mercy! Thanks , Mark from PA...

I finally got tired of this sound and went to the dealer. It was the idle air control value. The part was $175, and the labor $140, for a total of $315. Hopefully this will help someone in the furture, Mark...